Constant bearing course homing missile

ABSTRACT

A passive or semiactive homing missile using an optical sensor. The sensor includes a wide-angle lens and a quadrature detector. When a moving target is acquired, signals are generated to turn the missile toward the target. These signals are integrated and are used to turn the sensor to lead the target. The missile will eventually settle on a constant bearing (collision) course with the target. If the target makes changes in speed or direction, the missile will change direction to re-establish a collision course to the target.

rig

llite States Patent [191 Evers-Euterneck Oct. 15, 1974 CONSTANT BEARING COURSE HOMING MISSILE [75] Inventor: Ernst T. Evers-Euterneck,

Huntsville, Ala.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

[22] Filed: Mar. 6, 1973 [21] Appl. No.: 338,476

[52] US. Cl. 244/3.l5, 244/3.l7 [51] Int. Cl. F4lg 7/00, F4lg 9/00, F4lg 11/00 [58] Field of Search 244/315, 317; 343/55 MM [56] References Cited UNITED STATES PATENTS 3,041,011 6/1962 Dhanes 343/5 MM 3,416,752 12/1968 Hembree ..244/3.17

3,712,563 1/1973 Alpers 244/3.17

Primary Examiner-Samuel Feinberg Assistant ExaminerThomas H. Webb Attorney, Agent, or FirmEdward J. Kelly; Herbert Berl; Aubrey J. Dunn [5 7 ABSTRACT A passive or semiactive homing missile using an optical sensor. The sensor includes a wide-angle lens and a quadrature detector. When a moving target is acquired, signals are generated to turn the missile toward the target. These signals are integrated and are used to turn the sensor to lead the target. The missile will eventually settle on a constant bearing (collision) course with the target. If the target makes changes in speed or direction, the missile will change direction to re-establish a collision course to the target.

3 Claims, 2 Drawing Figures TRIGGER O l7d l8 TRIGGER j d l-v MOTOR LIMITER i1 CONSTANT BEARING COURSEsHOMING. MISSILE BACKGROUND OF THEJIN-VENTION .Various .types ,of homing .missiles are :known :in .the

art. Theseinclude ,those;using active, semiactive, and

passive homing. Regardless of the type, these missiles usually engage atarget withapure pursuitcourse. Any

otherttypeofcourse.normallyrequiresa complex-guidance computeron boardthemissile. Asis-well known, :the pure pursuit coursefhas-greater:timeeofsflightttotarget than acollision course and requiresihighmurnrates not required "by a collision course. 311115 thus advanta- ,geous.to'haveonesmissileflya collision course, if practical. The instant invention ,makes s ch .a ,thing practical, with a relatively simple system.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of the invention. FIG. 2 isa schematicdiagtamofa control loop .of the invention.

DETAILED DESCRIPTION OF THE lNvEl l'llON Referring now to FIG. 1, one sees missile having a transparent nose 1! and control fins 1,2 and 13. It should be understood that fins 12 and 13 are each half of a pair of fins, with the .drawing not showing the other half of 13, but showing both 112a and 12b. Naturally, the missile includes the usual rocket engine and warhead (both not shown). It is assumed in the invention that the missile travels with no roll at a constant speed until target engagement. The missile may be launched by a booster engine and maintained in speed by a sustainer engine, in the well known manner. Until a target is sighted, the missile may cruise under control of an autopilot. When a target is sighted, the instant invention begins to work.

The invention includes a wide-angle lens (fisheye) together with a matrix sensor such as quadrature detector in nose ll of the missile. Lens 14 and detector 15 are supported by frame 16. The outputs from the four quadrants of detector 15 feed respective triggers 17a17d. These triggers block signals from 15 below some threshold level. The outputs of Fla-17d feed inputs of respective AND gates l8a-18d. The output signals a, b, c, d from l8a-l8d may respectively be indicative of a target above or below the longitudinal axis to the missile, and port and starboard of the axis. These outputs a-d are applied to respective limiters l9a19d to give a constant value to any output from gates 18a-18d. These constant outputs are amplified to higher levels in amplifiers 200-2011. with respective amplified outputs applied to servo motors 21 and 22. The signal treatment used results in a bangbang" control system. Thus far. a missile capable of pure pursuit has been described, inasmuch as lens 14 and detector 15 have not been described as movable. There are three 2 alternatives at this point: 1) :14 and '15 can be fixed (strapped-down) to the missile body and notamovable with respect to the body,.2) l4 and :15and missilebody l0 canbecontrolled-to track the'target, and '3) :l4and .15,can-becontrolledto:track=the:target and themissile controlled tolead the target. The'first two of thesealternatives areused in the artand usually involve pure ,pursuitcourseszto'the target. The instantinvention uses alternative 3 .and is thereby .able to fly a collision course with the target'This is accomplished by feeding the signals applied to motors 21 and 22 to respective summers23and 24. If the signals from 20a-20d are derived fromtarget radiation (passive), they willbe rectangular waves, 23 and 24 will be integrators, and 23 and 24 .will provide triangular output waves to respecluminated by a pulsed laser or the like for semiactive homing, 15 will receive pulses and 23 and 24 will 'be accumulators.

FIG. 2 shows the simplified control 'loop for one axis .of rotation (pitchor yaw) for the inventive missile. As can be seen, the angular motion of the line-of-sight, and

motion from the sensor drive 30 (equivalent to servo motor .25 or 26) are effectively added, as schematically suggested by summing point 31, and the motions resulting from missile movement are subtracted in this point, with the sum-difference affecting the output of 32 32 corresponds to 14, 1'5, and 16 of FIG. 1). The output of 32 affects controls 33 to cause rotation of the missile about an axis (pitch or yaw). Box 33 corresponds approximately to ones of elements 17-22 and 12 or 13 of FIG. 1. The control signals for drive 30 are derived in summer 34, which corresponds to element 23 or 24 in FIG. 1. The sensor and control may have hysterysis curves as shown in the boxes.

Operation of the invention should be readily understood, in view of the drawings and of the detailed description above. One may fairly assume that the missile has been launched, has dropped its booster, has roll stabilized, and is cruising at constant speed on its sustainer engine. When its sensor detects a target, the missile, because of its bang-bang controls, executes a coarse maneuver toward the target, then starts a fine oscillation about the line-of-sightto the target. The signals used to execute the maneuvers are summed and asymetries from the bang-bang dwell times cause net output signals, which output signals are used to rotate the sensor contrary to the rotation of the line-of-sight in space. The turning velocity of the sensor with respect to the missile axes must be in accordance with the inequality mnx'. missile svuxor lim of sight where w is angular velocity. The bang-bang controls gradually establish symmetrical limit cycles and the average sum in the summer becomes 0. If the target tries evasive maneuvers, the missile automatically readjusts for a collision course.

While a specific embodiment of the invention has been shown and described, other embodiments should be obvious to one skilled in the art. For example, the triggers l7 and limiters 19 could be combined; or the limiters might be inserted between AND gates 18 and the triggers. Amplifiers 20 might be inserted between and the triggers, between the triggers and the AND gates, or between the AND gates and the limiters. Servo motors 21, 22, 25, and 26 may have substituted therefor pneumatic or hydralic activators. Although specifically described as usable against moving targets, the inventive missile would obviously be usable against fixed targets.

1 claim:

1. A homing missile having an elongated body with a longitudinal axis and yaw and pitch control means and including: optical sensor means including a wideangle lens and a matrix detector and means for supporting said lens and detector; at first set of respective operators for said control means; logic means connected to said detector for providing output control signals as inputs to said operators; a pair of summers having inputs connected to the inputs of said operators and each having an output; and a second set of respective operators attached between said body and said means for supporting and having inputs connected to said outputs of said summer.

2. The missile as defined in claim 1 wherein said summers are integrators.

3. The missile as defined in claim 1 wherein said sum- 

1. A homing missile having an elongated body with a longitudinal axis and yaw and pitch control means and including: optical sensor means including a wide-angle lens and a matrix detector and means for supporting said lens and detector; a first set of respective operators for said control means; logic means connected to said detector for providing output control signals as inputs to said operators; a pair of summers having inputs connected to the inputs of said operators and each having an output; and a second set of respective operators attached between said body and said means for supporting and having inputs connected to said outputs of said summer.
 2. The missile as defined in claim 1 wherein said summers are integrators.
 3. The missile as defined in claim 1 wherein said summers are accumulators. 